Ammunition



Jan. 3, 1933.

W. H. WOODFORD AMMUNITION Filed March 19, 1930 i ATTORNEYS.

for using such a lubricant as material 0 with the steel surface exposed.By after-corrosion is meant the as y . residues from some types ofammunition WATSON H. WOODFOBD, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR T0REMINGTON S COMPANY, INC., A CORPORATION OF DELAWARE istr'UNITIONApplication filed March 19, 1980. Serial No. 486,988.

5 wall of the gun bore a coating or film which will effectivelyprotect-the bore against corrosion even under the most adverseconditions of humidity and temperature.

It is a further object of the present inven- 11: tion to provide aprojectile coated with a material which presents a dry surface and is atthe same time highlyefiective as a lubricant for the projectile duringits passage through the bore of the gun. The necessity grease, whichpossesses many disadvantages, is thereby dispensed with. I

It is a further object'of the present invention to provide a projectilecoated with a resenting a highly lustrous and attractive nish, andwhich, in addition, is not susceptible to rapid oxidation or corrosion,and which thereforegives good protection against deterioration of theprojectile itself. The evil known as after-corrosion in gun barrels hasfor a long time been a troublesurface onex posure to the atmosphere willrust, and this is likewise true in connection in the bores of. guns. 7

corrosion which occurs in the bores of guns after shooting, the activityof which corrosion. has been greatly augmented heretofore the deposit,inthe bores of the guns, of

when fired in the guns; 7 This has been especially true in the pastwhere ammunition priming mixtures were used containing such 40 aningredient as potassium chlorate, which leaves hygroscopic residuesjinthe gun bore, which residues become lodged in the fissures and toolwounds of the bore surface, and which attractmoisture from theatmosphere,

in the presence of which aravaging corrosion of the steel of'thebor'etakes place.

Efforts to overcome after-corrosion have for the most part been directedtoward the discovery of ingredients for the explosive constituents ofammunition which would not w some problem. I As is well known, any steelonly satisfy the rigid ballistic and stability requirements, but would,in addition, leave no residues of a hygroscopic nature, and which wouldtherefore assist in preventing after-corrosion in gun bores. Suchammunition has been successfully produced and used, but it is to benoted that this ammunition does not in a positive manner preventcorrosion in the gun bore, inasmuch as it does not leave a protectivecoating in the bore of the gun, but merely is not capable of leavingobjectionable residues of a nature which might promote corrosion. v I

Further methods of combatin the evil of after-corrosion have involved te provision of certain ingredients in the explosiveconstituents ofammunition which appear to react with the material forming the bulletsurface to actually form a corrosion preventive film in the bore of thegun in which the ammunition is fired. Such ammunition has been producedand used with success, but in thls ammunition the available ran e in thechoice of explosiveingredients, w ich will successfully attaintheseresults is quite limited. Itis obviously highly desirable thatammunition be produced which is capable of preventmg corrosion in thegun bore without the necessity thereby' 'oflimiting the range in thechoice and selection of successfully operative ingredientsfor theexplosiveconstituents of this ammunition. Furthermore, inthisfammunition the bore coating characteristics appear to be dependentupon the joint' use of particular explosiveingredients,'together with abullet liavinga surface of a particular material. In connection withthis am munition tests haveindicated that success in forming aprotective coating in the gun bore is apparently due to some form ofreaction between the explosive'ingredients'and bullet material. It isdesirable that corrosion pre-' ventive ammunition be produced in. whichany of the common types of projectiles, already in use, may be utilized,and in which the successful formation of a bore'protective coating-maybeefiected without dependence upon'any form of reaction between theingredients of the ammunitionand the material of the projectile. Thepresentinvention aims In metal fouling, fragments of metal are torn fromthe bullet and deposited as isolated patches in the gun bore, and asrepeated 'firmgs take place this fouling accumulates,

resulting in impaired acuracy, reduction of bore diameter, as well asrendering the gun unsafe. Grease has been much used as a lubricant onbullets to prevent metal fouling, but the use of grease is attended bymany serious disadvantages, such as the difliculty of retaining thegrease on the projectile and the undesirable accumulation of foreignmatter by the grease. Various so-called dry lubricants have beenproposed, most of which constitute a soft metal applied as a jacket ordeposit on the projectile. The present invention contemplates theprovision of a projectile coated with a metal which not only functionsto prevent bore corrosion but also constitutes a dry lubricant ofsuperior bullet lubricating qualities and which very effectively acts toprevent metal fouling.

' According to the present inventionthehereinbefore mentioned and stillfurther objects are fulfilled, as will be apparent from the followingspecification, by the application of the metalcadmium to projectiles,preferably in the form of coatings applied to the surfaces of theprojectiles.

The natural corrosion preventive properties of cadmium are well known. Acadmium coating on a steel surface is known to be high- 1y efficient inprotecting the steel against rust, this coating being superior in manyrespects to coatings of other metals which have been long used for rustprevention, such for example as zinc and tin. The element cadmium standsnear the element iron in the electromotive series and will notdeteriorate as rapidly from anodic attack as other metals more remotefrom iron in the series. At the same time, cadmium is electro-positivewith respect to iron and will protect iron in accordance with wellestablished electro-chemical principles. The utilization of these andother well known desirable properties of cadmium is contemplated inconnection with the pres ent invention. In addition, the discovery ofheretofore unknown properties of cadmium is involved as an importantphase of the invention.

It has been discovered in connection with experiments leading to thepresent invention that new and highly advantageous results are obtainedwhen projectiles coated with cadmium are fired in guns. A gun barrelhaving such projectiles fired therein is found to be left with a highlylustrous coating. on the walls of the bore. The coating'or film thusformed is very thin and is uniformly distributed throughout the bore.Thisfilm fills the microscoplc fissures and tool wounds in the steel ofthe bore and prevents accumulation of hygroscopic residues which wouldattract and hold moisture and thereby promote corrosion. At the sametime thefilm serves to act as a bar against contact of the steel withthe atmosphere and thus, in 'a positive manner, actually preventscorrosion of the bore surface. In addition, considering theelectrochemical properties heretofore mentioned, the higher electrodepotential of cadmium in the electromotive series causes the cadmium toguard the bore steel against galvanic attack, and at the same time theproximity of cadmium in the series assures the cadmium against rapiddeterioration by anodic attack. Tests have demonstrated that gunbarrels,after having a few cadmium plated bullets shot therein, are capable ofwithstanding exposure to severe atmospheric conditions without a sign ofcorrosion in the bore. In one instance, several cartridges havingcadmium plated bullets were fired in a barrel, and this barrel was thenplaced in a chamber of heated and highly humidified air. Afterconfinement of this barrel to this chamber for a period of over twoweeks, examination showed the bore to be bright and entirely free fromrust, While parts of the barrel, other than the bore, were found to beheavily rusted. This test was carried on in its entirety without in anyway cleaning or treating the bore of the barrel, other than applyingcadmium as above described. Repeated firing of cadmium plated bullets ina gun has shown that the protective coating or film in the bore remainsthin and uniformly distributed, and that the diameter of the bore is notmaterially altered even after a large number of bullets have passedthrough the bore.

The projectilemay be provided at its surface with cadmium by anysuitable means. The projectile may be dipped into a molten bath ofcadmium, if desired. Or, the molten cadmium may be applied to theprojectile as by spraying; or the coating may be formed by electricaldeposition, or by any other suita l e depositing method. Further, thecoating may be applied as a previously formed jacket, plate or band,'etc., if desired. In-

asmuch as electrical deposition affords a means whereby the thickness ofthe coating may be easily controlled, and as only a very thin coating ofcadmium is required to perform the desired results successfull I preferto coat the projectiles by this met od. The well-known electrical barrelplating process, utilizing a cadmium cyanide solution.

constitutes a very suitable plating method for accomplishing thepurposes of the present invention. J p

The entire surface of the projectile may be cadmium plated, therebycausing the projectile to present an attractive surface over its entirearea. After plating with cadmium, the surface may be polished orfinished in any suitable manner, thus providing a bright surface whichis found to be capable of holding its lustre over a long period of time.It will be understood, however, that it is not essential to coat theentire surface of the projectile with cadmium, but that the abovedescribed bore coating effects may be obtained by providing cadmium ononly such portions of the projectile which engage the rifling of the gunor which contact the bore surface. In projectiles 'of the type havingrifling bands formed thereon the cadmium may beconfined to the riflingband only, if desired. I prefer, however, to coat the entire projectilein order to obtain the attractive finish as Well as the protection tothe projectile itself, which cadmium affords.

It will be understood also, as mentioned above, that the cadmium may beapplied to the projectile as a previously formed jacket, if desired,after methods known in the art in connection with jackets of othermaterials. However, due to the fact that but a very thin coating ofcadmium is required, and for the sake of economy, it is preferred toapply the cadmium to the projectile by some form of depositing process.

In the drawing, which forms a part of this specification, there areillustrated on an enlarged scale several representative types ofprojectiles embodying the present invention.

In Fig. 1 is shown in elevation, partly in section, one type ofprojectile embodying the invention.

In Fig. 2 is shown a similar view of another type of projectileembodying the present invention.

In Fig. 3 is shown a similar view of still another type of projectileembodying the present invention.

The projectile of Fig. 1 is a standard lead bullet of the type popularlyused with small calibre ammunition, such as for the .22 calibre rifle.The bullet proper, indicated at 10, is formed of lead, and a rifle band11, is formed on its outer surface integral with the body of the bullet.The entire surface of the bullet is provided with a thin coating orplating 12 of cadmium, which besides serving in the capacity of forminga protective coating in the gun bore, serves also as a protcctivecoating of attractive appearance for the bullet itseL The projectileillustrated in Fig. 2 is a rifle bullet of the mushrooming type. Ajacket 13, of copper, gilding metal, or other metal or alloy, is filledwith a core 14 of lead or material having high percentage of lead. Thenose of this projectile is provided with an aperture 15, and the jacketto the rear of this aperture is weakened as at 16 to facilitatemushrooming of the projectile on striking an object. The wholeprojectile-including the interior of the aperture is plated'with a thincoating 17 of cadmium. The coating being very thin and the metal cadmiumbein sufficiently soft, the mushrooming qualities 0 this bullet are notmaterially affected, while at the same time the many advantageousresults to be obtained from a cadmium coating, as hereinbefore pointedout, are at the same time obtained.

In Fig. 3, there is shown a rifle bullet of the ordinary jacketed type.A jacket 18 of copper, gilding metal, cupro-nickel or ot er metal oralloy, surrounds a core 19 of lead or metal having a high percentage oflead. The whole outer surface is provided with a thin coating 20 ofcadmium.

It will be obvious that a similar coating of cadmium may be provided onmany types of projectiles other than the three types illustrated, andthat like benefits may be obtained from such provision. The termprojectile as used in the specification and following claim is usedgenerically-and is to be understood as referring to projectilesgenerally, including projectiles for ordnance, bullets for small armrifles and smooth bore guns, as well as ball-shot. The bore coatingproperties of cadmium are apparently entirely independent of anyreaction of this metal with any of the explosive constituents ofammunition, and therefore cadmium coated projectiles may be successfullyused in conjunction with ammunition generally. regardless of theaccompanying explosive constituents of the ammunition.

Although the invention has been described with reference to cadmiumalone as a coating in the form of a plating, it is to be understood thatvarious forms of cadmium amalgams and cadmium alloys may be used asalternatives if desired. It has been found that excellent results are tobe obtained from cadmium alone, and that it is unnecessary to complicatethe process of coating by introducing other materials.

In the specification and following claim the terms coated with cadmiumand coating of cadmium are used as referring to a material containingcadmium, either alone or alloyed with other materials, constituting aportion only, or the entire surface of a projectile; and these termsrefer to the application of such coating by any known means, includingapplication by previously formed jackets, bands, etc., or by anysuitable manner of depositing the coating on the projectile, or byalloying the coating with the material of the projectile.

It is to be understood that the embodiments of the present invention asshown and described are purely illustrative, and that the scope of theinvention is not to be limited thereby except insofar as is defined inthe followmg clalm.

I claim: Y A projectile havingbapplied thereto a. coat- 5 ing of cadmiumcapa le of forming a corrosion preventive film on the walls of a. borewhen the ro'eetile is fired therein. WA S N H. WOODFORD.

